1. Field of the Invention
The invention relates to a knife sharpener rollable on a support.
2. Description of the Related Art
In a knife sharpener of the type known from U.S. Pat. No. 2,469,797, a regular grinding disc is enclosed resiliently between the two rollers whilst the respective support surfaces are formed by conical metal caps in the hub region of the rollers. The situation is similar in knife sharpeners according to U.S. Pat. Nos. 2,498,018 and 3,691,700 with the differences that, in the devices disclosed therein, the rollers on both sides are not subjected to any spring force, and the support surfaces are integrated in the two rollers. In each case, the knife blade to be sharpened is drawn in corresponding inclined position in succession through the two substantially V-shaped slots on the left and right of the grinding disc while the knife sharpener rolls on the support (for example, a table). The respective flank of the grinding disc slides in considerably varying direction on the cutting edge to be sharpened, giving a sharpening which is not very durable. In addition, the necessity of sharpening the blade in two successive operations in which it must additionally be held in opposite inclined positions has proved disadvantageous.
On the other hand, in the knife sharpeners disclosed in BE-PS No. 556,718 and DE-GM No. 1,867,319, grinding discs are disposed in pairs and pressed resiliently against each other and have intermeshing toothed rings on their end faces. The toothed rings form a V-shaped gap therebetween the peripheries of which are inclined with respect to each other. The knife blade to be sharpened in drawn through said gap whilst the grinding discs are driven separately therefrom. In this case, although only a single operation is necessary for the sharpening, the grind obtained with a grinding direction running parallel to the cutting edge is again not very durable.